other:python:misc_by_jyp
Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
|
other:python:misc_by_jyp [2022/05/23 16:01] jypeter [numpy related stuff] Changed the VIEW update warnng example |
other:python:misc_by_jyp [2022/12/12 12:11] jypeter Added the "Storing objects and data in a file" section |
||
|---|---|---|---|
| Line 228: | Line 228: | ||
| </code> | </code> | ||
| + | |||
| + | ==== Storing objects and data in a file (shelve and friends) ==== | ||
| + | |||
| + | The built-in [[other:python:jyp_steps?s[]=shelve#the_shelve_package|shelve]] module can be **easily** used for storing temporary/intermediate data | ||
| + | |||
| + | More options: | ||
| + | * Some [[other:python:jyp_steps#data_file_formats|non-NetCDF]] file formats | ||
| + | * Working with [[other:python:jyp_steps#netcdf_filesusing_cdms2_xarray_and_netcdf4|NetCDF]] files | ||
| ==== Sorting ==== | ==== Sorting ==== | ||
| Line 248: | Line 256: | ||
| ==== numpy related stuff ==== | ==== numpy related stuff ==== | ||
| + | === Using a numpy array to store arbitrary objects === | ||
| + | |||
| + | The numpy arrays are usually used to store [[https://numpy.org/doc/stable/reference/arrays.scalars.html|scalars]] of the same type (see also the [[https://numpy.org/doc/stable/reference/arrays.dtypes.html|Data type objects (dtype)]]), very often numerical values. | ||
| + | |||
| + | It is also possible to store **arbitrary** Python objects in an array, rather than using nested lists or dictionaries! | ||
| + | |||
| + | <code>>>> some_array = np.empty((2, 3), dtype=object) | ||
| + | >>> some_array | ||
| + | array([[None, None, None], | ||
| + | [None, None, None]], dtype=object) | ||
| + | >>> some_array.shape | ||
| + | (2, 3) | ||
| + | >>> print(some_array[-1, -1]) | ||
| + | None | ||
| + | >>> some_array[-1, 0] = filled_contour # e.g. save an existing cartopy filled contour object | ||
| + | >>> some_array | ||
| + | array([[None, None, None], | ||
| + | [<cartopy.mpl.contour.GeoContourSet object at 0x2ab679e8bf10>, | ||
| + | None, None]], dtype=object)</code> | ||
| + | | ||
| === Dealing with a variable number of indices === | === Dealing with a variable number of indices === | ||
other/python/misc_by_jyp.txt · Last modified: 2024/04/19 12:02 by jypeter
